This invention concerns a system for launching a lifeboat, rescue craft or like vessel, hereinafter referred to generally as a lifeboat, whether of solid or inflatable construction, from a fixed or semi-submersible marine platform or other structure.
An object of the present invention is to provide a safe and reliable system for launching such a lifeboat from an elevated position on the structure and for towing same to a safe distance therefrom.
The system is intended to overcome the difficulties and dangers encountered when launching lifeboats, particularly on the weather or windward side of, for example, a drilling platform where there is a tendency for the boat to be driven into the legs and pipework of the platform thus preventing rapid escape, for example, in the case of fire and when burning debris may fall into the sea from a position directly above the boat.
Several systems have been proposed for this purpose, the most successful of which has been described in our International patent application WO 91/03398 which referred to a system in which a submerged buoyancy device is tethered to the bow of a lifeboat suspended, before launch, on single or double davit falls, by a cable which is retained by a release mechanism fixed near the base of the structure and passed around a submerged guide member fixed at a similar level on or near the sea bed but at a distance off the structure such that when the cable is released as the boat is lowered onto the surface, the rising buoyancy device tows the cable and thus the boat away from the structure.
The present invention may be distinguished from the system earlier described by several features of modification and improvement which have been developed in the interest of increased efficiency and safety, but which in no way detract from the basic concept defined in our earlier patent application.
According to the present invention, there is provided a system for launching a lifeboat from an elevated position on a structure such as an offshore drilling platform, and for towing the lifeboat to a distant position away from the structure, the system comprising a submerged buoyancy device tethered to the lifeboat by means of a towing cable which passes from the lifeboat to the submerged buoyancy device, and a submerged guide member fixed to the seabed at or in the region of the distant position to which the lifeboat is to be towed, said towing cable passing around said guide member between the lifeboat and the buoyancy device; characterised in that the towing cable extends upwardly directly from the guide member towards the surface and towards the lifeboat.